The muscles that help hold the upper arm in the shoulder joint (the rotator cuff muscles) can get pinched (shoulder impingement syndrome), become inflamed (tendinitis), or can tear partially or completely.
(See also Overview of Sports Injuries.)
- The shoulder is painful when the arm is moved over the head and later, even when the arm is not moved.
- Exercises help.
The rotator cuff consists of the muscles that attach the shoulder blade to the head of the humerus. The rotator cuff strengthens the shoulder joint and helps rotate the upper arm.
Anatomy of a Shoulder Joint
Rotator cuff pinching (impingement) and tendinitis often occur in sports that require the arms to be moved over the head repeatedly, such as pitching in baseball, lifting heavy weights over the shoulder, serving the ball in racket sports, and swimming freestyle, butterfly, or backstroke. Repeatedly moving the arm over the head causes the top of the arm bone to pinch the rotator cuff muscles against the top part of the shoulder blade and can result in inflammation and swelling of the muscles. If the movement is continued despite the inflammation, the tendon can weaken and tear.
Even without overuse and chronic inflammation, the rotator cuff can be torn suddenly by a powerful movement (such as a severe stretch or pull) or a fall.
Shoulder pain is the main symptom. At first, the pain occurs only during activities that require lifting the arm over the head (impingement syndrome). Pain is worse when lifting the arm between 60 and 120 degrees away from the side. Unless effectively treated, the shoulder may later become painful at rest (tendinitis), often particularly at night, disrupting sleep. If the tendon tears, normal outward turning of the arm at the shoulder is weak or impossible.
- A doctor's evaluation
Doctors make the diagnosis based on the person’s symptoms and examination findings. Magnetic resonance imaging (MRI) sometimes is needed to rule out a tear of the rotator cuff muscles.
The shoulder can be rested by keeping the arm in a sling for a couple of days if pain is moderate or severe. Exercises that involve raising the arm above the level of the shoulder, especially against resistance, should be avoided. Once the shoulder can be moved through its range of motion without pain, the rotator cuff muscles can then be strengthened. Exercises to strengthen some of the muscles restore balance to the rotator cuff and decrease impingement during activities that involve reaching overhead. If the pain is severe, doctors may prescribe anti-inflammatory drugs or sometimes inject a corticosteroid into the space above the rotator cuff (bursa).
Surgery is sometimes needed when the rotator cuff is torn or tendinitis does not resolve with other treatments. Surgery removes excess bone from the shoulder, creating a larger space for the rotator cuff and thus preventing pinching of the rotator cuff when the arm moves above the head. If the rotator cuff is torn, surgical repair is usually recommended.